Buying Glasses Online
Specs or glasses, more formally known as eyeglasses or spectacles, are fundamentally frames containing prescription lenses worn in front of the eyes, commonly for visual acuity correction, eye protection, or for protection from ultraviolet rays.
Current Eyeglasses are usually supported by pads on the nasal bridge and by temples placed over the ears. Early examples include the pince-nez, monocle, and lorgnette.
Eyeglass frames are usually made from metal or plastic. Lenses were to begin with made with glass, but many are now manufactured from various types of metal plastic, including CR-39 and polycarbonate. These materials lower the peril of breaking and weigh less than glass lenses. Some plastics also have more advantageous optic attributes compared to glass, for example better transmission of visible light and greater absorption of ultraviolet light. Some plastics have a bigger index of refraction than most types of glass; this may be helpful in the creation of corrective lenses worked to correct various vision abnormalities such as nearsightedness, permitting thinner lenses for a given prescription. Newer plastic lenses, called izon, can also correct for the higher order optical aberrations that naturally happen along the surface of our eye. These lenses produce sharper vision and help with the halos, starbursts, and comet-tails often associated with night time driving glare. Wavefront guided LASIK surgery
may also correct for the higher order aberrations.
Scratch-resistant coatings may be applied to almost all classes of plastic lenses giving them analogous scratch resistance to glass. Hydrophobic coatings designed to ease cleaning are also forthcoming, as are anti-reflective coatings thought to cut down glare, ameliorate night vision and make the wearer’s eyes more visible.
